Detachable attachment-plug.



G. B. THOMAS.

DETACHABLE ATTACHMENT PLUG.

APPLICATION man JULY 11. 1914.

1,21 6,883. Patented Feb. 20, 1917.

a nve ntoz UNITED STATES PATENT OFFICE.

GEORGE B. THOMAS, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE BRYANT ELECTRIC COMPANY, OF BRIDGEPORT, CONNECTICUT, AL CORPORATION OF CON- nncrrcur.

DETACHABLE ATTACHMENT-PLUG Patented Feb. 20, 1917.

Application filed July 17, 1914. Serial No. 831,586.

To all whom it may concern:

Be it known that I, GEORGE B. THOMAS, a citizen of the United States of America. and residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented a certain new and useful Improve ment in Detachable Attachment -Plugs, of which the following is a specification.

My invention relates to detachable attachment plugs and the object of my invention is to provide a device of this character, simple in construction and efiicient in operation.

Referring to the accompanying drawings,

Figure 1 is a vertical section through an attachment plug in which my invention is embodied in one form and in which the detachable cap is shown separated;

Fig. 2 is an inverted plan of the cap;

Fig. 3 is an inverted plan of the thumb piece of the plug body;

Fig. 4 is a plan of the terminal button of the plug;

Fig. 5 is a plan of the cap;

Fig. 6 is a plan of the thumb piece;

Fig. 7 is an inverted plan of the terminal button; and

Fig. 8 is a partialsection through the plug showing the engagement of one of the blades of the cap with one of the terminals carried by the plug body.

The body of the present attachment plug comprises at its entering end a button 10 of insulating material, and at its outer end a thumb piece 11 of insulating material, by means of which the plug body may be screwed into the .receptacle. The two buttons are secured together in assembled condition by the screw shell terminal 12, the lower end of which is provided with a flange 13 overlying a shoulder 14 in the lower face of the button 10, while its upper edge 15 is spun into an annular recess 16 in the thumb piece 11. The center contact 17 of the plug is here shown as a metallic washer engaged by the head of the screw bolt 18 which passes up through the button 10 and engages the strap 19, lying on the upper face of this button. Spring terminals 20 and 21 are mounted on the upper face of the button by means of screws 22 and 23, the heads of which lie in bays 24 and 25 formed in the lower face of the button. Screw 22 is threaded into the strap 19 which overlies the base of the terminal 20 so that the latter is thus brought into electrical conof their respective contact chambers.

from the flange 13 of the screw shell into a the bay 25 and engages a nut 27, overlying the base of the spring terminal 21, so that the latter is thus brought into electrical connection with the shell terminal of the plug body.

The thumb piece 11 is provided with independent chambers 28 and 29 which, in the assembled position of the plugs, register with the spring terminals 20 and 21. The proper positioning of the thumb piece 11, with relation to the button 10, is determined by a rib 30 which takes into a corresponding recess 31 in the thumb piece 11. The chambers 28 and 29 are formed with flat sides 32 and 33 which constitute bearing supports for the blades 34 and 35, carried by the cap 36. When the blades are withdrawn the bowed portions of the spring terminals 20 and 21 press against the flat walls 32 and 33 Upon the insertion of the blades 34 and 35, the springs are pressed back into the chamber and the bowed portions overlie offsets m in the faces of the blades, thus serving to frictionally grip and retain the cap in inserted position.

To insure the insertion of the blades in contact with the side walls 32 and 33, guide slots a and 7) are formed in the upper face of the thumb piece 11, above the chambers 28 and 29 with one wall of each slot forming a continuation of the walls 32 and 33.

The cap 36 is centrally apertured at 37 to admit the cable 38 into the internal recess 39 which-affords room for a strain relief knot 40 in the wires. Ledges 41 and 42, formed on the opposite sides of the recess 39, receive the binding screw straps 43 and 44, secured by screws 45 and 46 to the cap. Blades 34 and 35 are integral with the straps 43 and are offset inwardly into register with the spring terminals 20 and 21. By arranging the straps 43 and 44 adjacent the marginal flange 47 of the cap, the binding screws 48 and 49 are separated as far as possible and the danger of short-circuiting through wire beards minimized.

The present construction greatly facilitates the assembly of the external and internal contacts of the plug body, since they are all mounted upon the button 10 before the thumb piece is positioned thereon, and the upper edge 15 of the screw shell 12 spun into the annular recess 16. The general construction is rugged and strong and the contact between the spring terminals in the body and the blade on the cap is very firm, owing to the fact that the blades enter the contact chambers 28 and 29 in engagement with the flat walls 32 and .33 thereof, so that they are not free to yield under the pressure of the spring contacts. The parts are all readily manufactured and assembled and the device as a whole is compact and eflicient.

I claim as my invention 1. A detachable attachment plug having a body portion having external and internal contacts and comprising at its'entering end an insulating button carrying said contacts and at its outer end a thumb piece of insulating material internally recessed to receive said internal contacts and externally recessed to receive an ofiset portion of one of said external contacts whereby said parts are held in assembled position.

2. A detachable attachment plug having a body portion comprising at its entering end a button of insulating material and at its outer end a peripherally recessed and internally chambered thumb piece of insulating material,'a screw shell carried by said button and spun into said peripheral recess in the thumb piece to hold the latter in assembled position, a, center contact carried by said button and internal contacts carried by said'button, said internal contacts being electrically connected to said center contact and screw shell respectively and projecting into said chambered thumb piece.

3. Adetachable attachment plug having a. body portion comprising a button at the entering end of the plug, and a thumb piece at the outer end of 'the plug, cooperating projection and recess on the adjacent faces of said partsto definitely locate the same with relation to each other, and to prevent relative swiveling, together with a screw shell carried by said button and engaging said thumb piece to hold the parts assembled.

4. A detachable attachment plug having a body portion comprising a button at the entering end of the plug. and a thumb piece at the outer end of the plug, cooperating rib and recess on the adjacent faces of said parts to prevent relative swiveling, said rib and recess extending only partially across the said adjacent faces to insure the correct positioning of said parts with relation to each other, and a screw shell carried by said button and engaging said thumb piece to hold the parts assembled.

5. A detachable attachmentplug having a body portion comprising at its entering end a button of insulating material carrying external and internal contacts, and at its outer end a thumb piece of insulating material having chambers to receive said internal contacts, each of said chambers having at least one flat abutment wall against which the free ends of said internal contacts normally press, together with a detachable cap having blades adapted to enter said chambers in contact with said flat walls.

6. A detachable attachment plug having a body portion comprising at its entering end a button of insulating material carrying external and internal contacts, and at its outer end a thumb piece of insulating material having chambers to receive said internal contacts, each of said chambers having at least one flat abutment wall against which the free ends of said internal contacts normally press, and a guide slot atits outer end registering on one side with said flat wall. together with a detachable cap having blades adapted to enter said chambers through said guide slots in contact with said flat walls.

7. A detachable attachment plug having a body portion comprising at its entering end a button of insulating material carrying external and internal contacts, and at its outer end a thumb .piece of insulating material having flat-sided chambers to receive said internal contacts, said internal contacts being yieldably pressed toward the flat sides of said chambers, in combination with a cap having contact blades adapted to enter said chambers in contact with said flat sides and press said spring contacts away therefrom.

8. A detachable attachment plug having a body portion comprising at its entering end a button of insulating material carrying external and internal contacts, and at. its outer end a thumb piece of insulating material having flat-sided chambers to receive said internal contacts, said internal contacts being yieldably pressed toward the flat sides of said chambers, in combination with a cap having contact blades adapted to enter said chambers in contact with said flat sides and GEORGE B. THOMAS.

Witnesses G. W. Goonnmcn, H. M. WICHERT. 

